This invention relates to electromechanical energy conversion and, more particularly, to a motor having independently excitable. redundant sets of windings which ensure operation in the event of a failure in a winding or its associated drive circuits.
Electric motors are employed in numerous situations which range from the driving of toys to the positioning of aircraft control surfaces. In an electric motor which performs critical functions such as the positioning of aircraft control surfaces it is essential that the motor function properly to ensure the safety of the aircraft.
In the past, reliability of electric motors has been enhanced by tandem connection of two or more motors on a common shaft. Alternatively, a plurality of motors has been connected by differential gearing to ensure that, in the event of failure of one motor, one or more motors is still connected to the load to prevent loss of the drive function.
Such practices are disadvantageous in that a plurality of motors and their mechanical interconnection requires much space. In some applications, the necessity of the additional space would preclude the use of the plurality of motors. In some applications, as in the positioning of control surfaces in aircraft, the additional weight of the plurality of motors as well as the lack of space, would inhibit this approach.